1. Field of the Invention
The invention is concerned with a molding apparatus for finish forming and curing tread and track belts with any desired tread pattern thereon.
2. Prior Art
In the making and curing of tire tread and track belts it has been common to wrap one or more layers of an uncured elastomeric material such as rubber or the like, with or without reinforcement such as metal belting, fabric and the like, about a cylindrical core. The cylindrical core is selected to have a diameter equal to the desired inner diameter of the eventually-cured belt. Thereafter, the cylindrical core, with the elastomeric layers and the like attached thereabout, is generally placed in the center of a cylindrical mold which comprises a larger cylinder, which larger cylinder can include mold faces with desired tread patterns on the interior surface thereof, the diameter of the larger cylinder is reduced until it properly contacts the material wrapped about the inner core and the entire apparatus is heated to cure the elastomer wrapped about the inner core. In such an apparatus, the outer mold face cylinder can, of course, be constantly heated if desired but it is not possible to heat the inner core about which the rubber is wrapped because premature curing might then take place. What results is somewhat uneven heating and hence uneven curing of the elastomer into the form of a tire tread or track belt. In particular, metal bands within the tire tread or track belt are often displaced from their desired positions when cured in a prior art mold with a relatively high temperature gradient between the inner core holding the tire tread or track belt and the outer cylinder of mold faces. Also, the time of curing is relatively long since the inner core, at least, must be heated after it has been placed in the mold. Further, the repeated heating and cooling of at least the inner core is costly in energy.
It would be highly desirable to provide an apparatus and a process for curing tire tread and track belts wherein the belts were uniformally and relatively quickly cured from both their inner and outer circumferences while heating costs were minimized and wherein metal bands and the like within the tire tread and track belts were kept uniformally distributed by the uniform curing thereof. The present invention provides just such an apparatus.